The present invention relates to a semiconductor device, a semiconductor system including same, and a semiconductor device control method. The invention relates to a semiconductor device, a semiconductor system including same, and a semiconductor device control method which are suitable for correctly judging that, for example, any module has been coupled to and decoupled from a communication bus.
For data communication between a controller and a module, a communication scheme, I2C (Inter-Integrated Circuit) is widely used. In I2C communication, since a controller and plural modules can be coupled through a shared bus, the number of wiring lines for signal transmission can be decreased.
In I2C communication, after a controller (master) transmits a data write or read command to a module (slave), when the controller has received a reply (ACK signal) to the transmission from the module, it actually performs data write or read.
In this regard, after transmitting a data write or read command to a module, the controller can become aware of failure or decoupling of the module only when it has failed to receive a reply to the transmission from the module properly.
However, in such a framework, for example, let us suppose that the controller gives a command to perform steady operation to a module having a moving part, such as a motor; even if the module has been decoupled from the bus during its operation, the controller would misjudge that the module performs steady operation until giving a different command from the one for steady operation to the module. In consequence, there is a possibility of system malfunction occurring.
A solution to this problem is disclosed in Patent Document 1. A coupling detection device disclosed in Patent Document 1 includes a coupling detector circuit in which potential at point A varies when an external unit has been coupled to a coupling detecting terminal, an AD converter which outputs a digital signal corresponding to the potential at point A, and a coupling detection controller which judges whether or not an external unit is being coupled to the coupling detecting terminal according to a signal output by the AD converter. Thereby, a main unit (controller) equipped with the coupling detection device can judge the coupling/decoupling of an external unit promptly.